Introduction

Mark-recapture

  • Mark: disc-dangler tag
  • Tag as many fish as possible
  • Tagged fish mix with non-tagged fish
  • Recapture: subsequent tagging seasons & angling population
  • Population metrics

Helpful Websites

Striped Bass

striper

Background

  • Introduced from Atlantic Coast
  • Two plants (1879, 1882)
  • Spread quickly in our waters
  • Commercial fishing closed 1935

Biology

  • Born in freshwater
  • Spawning: mostly Sacramento River
  • Move throughout our rivers, bays, coastline
  • Legal-size (18") roughly age-3
  • Mostly inhabit open waters (pelagic)

  • One dorsal fin, spiny- & soft-rayed sections
  • Between 6 & 9 horizontal stripes

Data Collection

  • Fishery: dependent & independent
    • CPFV (aka Party Boat)
    • CDFW Striped Bass Tagging Program
    • CDFW Summer Townet Survey
    • CDFW Fall Midwater Trawl
    • CDFW San Francisco Bay Study
    • Salvage Monitoring

Mark-recapture (Tagging) Program

  • Ongoing since 1969
  • Affix one Peterson disc tag
  • Provides population metrics
  • Creel census (now defunct)

working trap

tag sides tag placement

Party Boat

Annual Harvest Rate

Length Frequency

Catch per Trap-Hour

Fraction (sub-legal v. legal)

Sturgeon

sturgeon

Background

  • Two species (Green & White)
  • Green (federally listed threatened 2006)
  • White (legal size 40-60" FL, 1 daily, 3 yearly)
  • Commercial fishing 1875-1901
  • Fishing mostly prohibited 1901-1953

Biology

  • Born in freshwater
  • Spawning: mostly Sacramento River (San Joaquin River)
  • Variable recruitment
  • Move throughout our rivers, bays, coastline
  • Mostly inhabit bottom (benthic)
  • Adult age-15
  • Long-lived

Identification

  • Lateral plate (scutes)
    – Green: 23-30
    – White: 38-48

  • Barbels
    – Green: closer to mouth than tip of snout
    – White: close to tip of snout than mouth

  • Green only
    – 1-2 plates behind dorsal fin
    – belly stripe

Data Collection

  • Fishery: dependent & independent
    • Sturgeon Fishing Report Card (since 2007)
    • CPFV (aka Party Boat; subset of Card data)

    • CDFW Sturgeon Tagging Program
    • CDFW San Francisco Bay Study
    • CDFW Salvage Monitoring
    • CDFW Native Fishes (20-mm)

Mark-recapture (Tagging) Program

  • Ongoing since 1954
  • Deploy trammel nets
  • Affix one Peterson disc tag
  • Provides population metrics

net fishing

sturgeon tagged

Report Card

  • How to, when to, why return – snail mail or on-line – by 31-Jan (year following the card) – conservation efforts

  • Did not fish v. Fished no catch

  • Use “tags” sequentially (001, 002, 003)

  • San Joaquin Codes (clarification)
    – 12 : Upstream Hwy 140 Bridge
    – 13 : Hwy 140 Bridge to Stockton
    – 14 : Stockton the Sherman Lake

Party Boat

Report Card (Summary)

   Year Issued ReturnRate    CC    IS GST WSTr WSTk
1  2007  37680       18.4    NA    NA 316 4666 1431
2  2008  53777       13.6    NA    NA 240 5103 1786
3  2009  72499       11.8    NA    NA 241 5807 1871
4  2010  66357       11.3    NA    NA 163 4372 1424
5  2011 112000       11.0    NA    NA 120 4276 2047
6  2012 112800       11.2 10796  1844 176 4224 1747
7  2013  50915       20.9  6849  3792 170 4473 2037
8  2014  49260       24.5  5978  6094 186 4680 2331
9  2015  48337       29.7  5523  8858 198 6214 2418
10 2016  47617       32.9  4491 11181 221 5074 2595
11 2017  44374       33.5  3646 11223 236 4891 2809
12 2018  44147       32.4  2796 11498 210 4163 2144

Annual Harvest Rate

Relative Abundance

Length Frequency

Conclusion (Questions)

  • Fishery Dependent & Fishery Independent
  • CDFW mark-recapture studies
  • Disc tag returns & Sturgeon Report Card return

  • Questions?